Boat hull construction to provide stern lift

ABSTRACT

A V-shaped boat hull is formed with a pair of side shelves which extend from the bow to the stern and at the stern end are made of substantially less depth to provide a planing surface which tends to lift the stern and maintain the hull level during both acceleration and deceleration of the boat.

United States Patent 1191 Peterson BOAT HULL CONSTRUCTION TO PROVIDE STERN LIFT [76] Inventor: Ronald M. Peterson,' 601 Continental Dr, Nashville, Tenn. 37209 221 Filed: Jan. 8, 1973 21 App]. N6; 321,726

[52] US. Cl. ll4/66.5 S, 114/56 [51] Int. Cl B631) 1/18 [58] Field of Search 114/66.5 P, 66.5 S, 66.5 R,

[56] References Cited UNITED STATES PATENTS Moesly 114/56 1451 May 7,1974

2/1967 Ross"; 114/56 FOREIGN PATENTS 0R APPLICATIONS 383,514 9/1924 Germany 114/665 R Primary Examiner-Albert J. Makay Assistant Examiner-Donald W. Underwood [57] ABSTRACT A V-shaped boat hull is formed with a pair of side shelves which extend from the bow to the stern and at the stem end are made of substantially less depth to provide a planing surface which tends to lift the stern and maintain the hull level during both acceleration and deceleration of the boat.

1 Claim, 6 Drawing Figures l BOAT HULL CONSTRUCTION. TO PROVIDE STERN LIFT BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to boat hulls and particularly to boat hulls having stern lifting planing surfaces.

2. Description of the Prior Art lthas been known to use trim attachments for giving added stern lift to boat bulls and typical references include U.S. Pats. Nos. 3,370,561 and 3,399,643. US. Pat. No. 1,805,131 teaches another type of planing attachment. The prior art has also taught the formation of shelf formations in the hull. See, for example, US. Pats. Nos. 1,296,155; 2,342,023; 2,423,860; 3,045,629 and 3,415,213. The cited prior art references are generally complex and have not met the need for a comparatively simple hull construction that can be massproduced and that will provide added stern lift to offset engine, gas and battery loads in small size pleasure craft of general utility. Furthermore, small size pleasure craft hulls of, say, in the range of to 25 feet have had a tendency to maintain a relatively high amount of wet surface when planing and this has substantially limited forward speeds. Another problem with conventional hull designs employed in small pleasure craft is that visibility over the bow is hampered by the fact that the bow tends to rise whereas such visibility would be improved were the hull to assume a more level attitude when building up speed. Still another problem experienced with conventional hull designs is porpoising a bow raising in rough water.

What has long been needed in small pleasure craft hulls which are intended for general utility and not specifically for high speed racing, high speed hydroplaning, and the like, is a hull construction which provides stern lift and maintains a more level attitude at all speeds and with good how visibility.

SUMMARY OF THE INVENTION The invention is directed to small pleasure boat hull constructions in the range of 10 to 25 feet and of a modified V-shaped design. More specifically, a standard V-shaped hull is modified by incorporating a shelf indentation on each side and whose depth is substantially less for a rearward minor portion than for a major forward portion. The transition between the two portions of each shelf is by a sloping ramp portion. The result is that the minorshelf portion provides added stern lift at all speeds and thus quickly causes the hull to plane and thereafter maintains the hull on a substantially level planing attitude. When dead in the water or until such speed at which planing is achieved, ample buoyant displacement for the stern of the boat is maintained by the minor shelf portion and sloping ramp shelf portion which are partially submerged. When planing has been fully achieved, however, the invention shelf is no longer in contact with the water thus reducing the wet surface required for planing to an absolute minimum. As a further advantage the novel side-shelf, stern lift arrangement efi'ectively serves as a spray rail and which deflects spray away from the cockpit area during forward motion of the boat. I

The general object is to provide an improved modified V-hull construction for small pleasure craft which can be mass-produced at an economical price. A more specific object is to provide a modified V-hull construction for small pleasure craft which enablesthe hull to remain substantially level at all speeds and during changes in speed whether increasing or decreaseing and at the same time minimizes the wetsurface used for planing.

DESCRIPTION OF THE DRAWINGS FIG. 1 is the type prior art boat hull over which this invention is intended to be an improvement and showing a portion rearwardly of the line of cut indicated in FIG. 2.

FIG. 2 is a perspective view of the underside of a boat hull having a construction according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 7 Referring to FIG. 1, there is shown a partial perspective bottom view of a typical prior art hull construction commonly used in small'pleasure boats. In such beats the outer keel 10 runs forward to the bow 11 (FIG. 2) to form a stabilizing skeg. In FIGQl the hull bottom is effectively provided by the surface bounded by the hull center line 12, the hull chines 13, 13 and the transom 14, 14 of transom 15. The standard hull side indicated at 16 is bounded by the chine-13, the transom edge 17, the sheerline l8 and the bow 11 (FIG. 2). With such a standard hull, the planing surface is generally that connecting dashed and solid line area bounded by points P-l, P-2 and some forward point P-3 along the center line 12. As is commonly known, when the standard and widely used V-shaped hull of thetype generally depicted in FIG. '1 is used, the boat tends to ride with the bow raised, with spray penetrating the cockpit, with bow visibility being obstructed, and with a marked tendency to take in water. over the transom anytime the speed is suddenly dropped.

In FIGS. 2-5 there is shown a standard boat hull as I shown in FIG. 1 but modified according to the invention. Comparing FIG. 1 with FIGS. 2-5, the keel 20 compares to keel l0, center line 21 compares to center line 12, hull chines 22, 22' compare to chines 13, 13, transom edges 14, 14 compare to transom edges 23, 23', transom 15 compares to transom 24, transom edge 17 compares to transom edge 25, and sheerline l8 compares to sheerline 26.

Referring further to FIGS. 2-5, it will be seen that according to the invention there is provided a pair of shelves 30, 31, only the rearward portion of shelf 31 being shown. Shelf 30 is explained by way of example and includes forward vertical guide surface 32 and rear vertical guide surface 32, the forward generally horizontal surface 33, the rearward generally horizontal planing surface 34 and the forwardly inclined connecting planing surface 35. Guide surfaces 32, 32' effectively form a lower hull side whereas surface 36, which faces 34 and 35.

In further comparison of the FIG. 1 hull construction with that of FIGS. 2-5, the planing surface of the hull construction of the invention is that bounded by the connected solid and dashed lines as defined by points P'-l, P'-2 and P'-3. Note should be taken here that for a boat of given width, depth, length and hull V-angle, a hull constructed according to the invention utilizes comparatively less planing surface and therefore has substantially less wet friction surface at full plane.

With the foregoing description in rnind, the operation of a hull according to the invention will next be described. At rest, the dead waterline (D.W.L.) is above surfaces 34, 34 and 35, 35'. As the hull starts forward and the pressure of the water against surfaces 35, 35 increases, there will be an increasing lift efi'ect on the stern as the bow also starts its usual rise. As the speed increases less and less of surfaces 35, 35 are in the water. When a planing speed in neared surfaces 35, 35'

. will be completely out of the water and surfaces 34, 34'

will for a short transitional time act as planing surfaces and then as speed increases, surfaces 34, 34 leave the water. At a speed characterized by full planing of said hull the only surfaces in contact will be those bounded substantially by the previously mentioned points P-l, P-2, and Pf-3. In this regard, it should again be noted that this final planing surface is of comparatively less than normal area for the same width, depth, length and V-angle and therefore has less frictional drag. The invention hull thus provides a lifting and leveling efi'ect prior to planing and at the same time decreases exposed wet surfaces once planing is achieved.

Before or after planing hasbeen fully achieved, porpoising or bow raising of conventional V-hull designed boats-is known to occur in moderately rough water. Porpoising is effectively prevented and a substantially level planing attitude is maintained under such conditions by the invention-hull due to the fact that any significant degree of bow raising will tilt the stern deeper into the water as shown in FIG. 6. Such tilting will cause the rear shelf portion 34 and sloping ramp portion 35 to be contacted by oncoming water, providing a stern lifting force (indicated by arrows) which counters the tendency of the bow to rise further.

.Another intersting and valuable aspect of the hull construction of the invention is that the usual spray as depicted in FIG. 5 is trapped by the shelf effect and is prevented from reaching the cockpit. Also shown in 33 and 34 may be conveniently used to support integrally molded flotation material 40 or to provide a shelf 41 for gear, e.g., water skis, etc.

While not specifically shown, use of the present invention indented shelf structure is contemplated for modified V-hull designs of the well-known cathedral hull type. On such cathedral hulls, side sponsons may be formed to include side shelf indentations according FIGS. 4 and'S on theinterior of the hull, shelf portions to the invention to provide the net lifting and leveling effect as previously described in connection with the more conventionalV-hull design shown in the drawmgs.

Many variations of the above described preferred form of the invention will appear to those skilled in the art without departing from the intended spirit and scope of the invention as defined by the following claim.

Having described the invention, what is claimed is:

l. A boat hull comprising a bottom having a longitudinal central portion comprising two substantially flat sections of rearwardly rectangular and forwardly tapered shape extending outwardly from their juncture at the hull center line at some predetermined V-angle and providing sufiicient total surface area to allow the hull to plane at high speeds solely on rearwardly disposed portions of such sections, having upwardly and vertically extending lower sidewalls at opposite sides of said central portion and being of shallow depth relative to the depth of the hull, said bottom having a pair of flat steps of narrow width relative to the rearward width of said sections and extending laterally outwardly from, substantially perpendicular to, and extending along each of said lower sidewalls for substantially the entire length thereof, said flat steps having a major forwardly disposed portion ata predetermined level above the normal dead waterline of the hull and above a minor rearwardly disposed portion thereof located below the normal dead waterline and having between said minor and major flat step portions a connecting forwardly inclined flat portion, upstanding upper hull sides at the outer edges of said steps and extending for; the length of the hull, a transom member joining said hull sides and bottom at the stern of said hull, the surface area, width and levels of said steps major and minor portions and the angle of said inclined connecting portion being selected such that as said hull progresses forward when gating speed the stern thereof is forced upward by the action of said steps at substantially the same rate as that of the bow and said hull at full forward speed is maintained substantially level and planes on a rear portion i only of said bottom flat sections.

7 3 UNITED smmg PATENT OFFICE CERTIFICATE OF QORRECTION Patent No. 3.808.999 Dated y 1.1914

Rowan-(5% Ronald M. Peterson It is certified thee error appears in me ebove-ideneifiei patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 22, "in" should be -is-.

Column 4, line 47 "gating" should be -gaining-.

Signed and sealed this 1st day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patent 

1. A boat hull comprising a bottom having a longitudinal central portion comprising two substantially flat sections of rearwardly rectangular and forwardly tapered shape extending outwardly from their juncture at the hull center line at some predetermined Vangle and providing sufficient total surface area to allow the hull to plane at high speeds solely on rearwardly disposed portions of such sections, having upwardly and vertically extending lower sidewalls at opposite sides of said central portion and being of shallow depth relative to the depth of the hull, said bottom having a pair of flat steps of narrow width relative to the rearward width of said sections and extending laterally outwardly from, substantially perpendicular to, and extending along each of said lower sidewalls for substantially the entire length thereof, said flat steps having a major forwardly disposed portion at a predetermined level above the normal dead waterline of the hull and above a minor rearwardly disposed portion thereof located below the normal dead waterline and having between said minor and major flat step portions a connecting forwardly inclined flat portion, upstanding upper hull sides at the outer edges of said steps and extending for the length of the hull, a transom member joining said hull sides and bottom at the stern of said hull, the surface area, width and levels of said steps major and minor portions and the angle of said inclined connecting portion being selected such that as said hull progresses forward when gating speed the stern thereof is forced upward by the action of said steps at substantially the same rate as that of the bow and said hull at full forward speed is maintained substantially level and planes on a rear portion only of said bottom flat sections. 